1. Field of the Invention
This application relates to methods of using access devices to perform minimally invasive surgery, such as procedures for stabilizing bone structures of a patient.
2. Description of the Related Art
Spinal surgery presents significant difficulties to the physician attempting to reduce chronic back pain or correct spinal deformities without introducing additional trauma due to the surgical procedure itself. In order to access the vertebrae to perform spinal procedures, the physician is typically required to make large incisions and cut or strip muscle tissue surrounding the spine. In addition, care must be taken not to injure nerve tissue in the area. Consequently, traditional surgical procedures of this type carry high risks of scarring, pain, significant blood loss, and extended recovery times.
Apparatuses for performing minimally invasive techniques have been proposed to reduce the trauma of posterior spinal surgery by reducing the size of the incision and the degree of muscle stripping in order to access the vertebrae. One such apparatus provides a constant diameter cannula, which is made narrow in order to provide a small entry profile. As a result, the cannula provides minimal space for the physician to observe the body structures and manipulate surgical instruments in order to perform the required procedures.
Once a doctor has exposed the vertebrae in some way, the most common treatment to reduce or eliminate degeneration of the spine or a portion thereof is fixation and/or fusion. Those conditions that compromise the spinal motion segments (adjacent vertebrae and the disc tissue or space in between) are often addressed by inserting a fusion device to promote bone growth between adjacent vertebrae. These devices are most commonly reinforced with a series of pedicle screws and rods to ensure minimal movement between adjacent vertebrae. These fixation devices provide load support for the spine, and can decrease the need for more extensive postoperative immobilization. Unfortunately, a narrow cannula is typically insufficient to perform one level spinal fixation procedures, which requires visualization of two vertebrae and introduction of screws, rods, as well as other large spinal fixation devices. Moreover, the pedicle screw fixation systems themselves require access to a larger area of the spine than the targeted disk area, increasing the trauma during surgery and increasing the time of patient recovery.